Fig. 2: SNAP-tag is an efficient tool for visualize the effect of pH on Bap-mediated multicellular behavior.
From: Bacterial biofilm functionalization through Bap amyloid engineering
a Schematic representation of Bap-SNAP labelling mechanism. b Scheme illustrating the effect of pH on Bap-mediated multicellular behavior. When S. aureus expressing Bap-SNAP is cultured in LB the pH of the media keeps neutral along the growth curve. In this culture conditions Bap is expressed at the cell surface of the bacteria. When S. aureus expressing Bap-SNAP is cultured in LB with glucose 0.5% (w/v) (LB-glu) the pH of the media is acidified when bacteria enter in stationary phase. Bap N-terminus is processed and N-terminal fragments start to self-assemble and ultimately form amyloid fibers that mediate cell-to-cell contacts. c Immunofluorescence showing localization of Bap in S. aureus expressing Bap-SNAP grown in LB and LB-glu media at 37 °C, 200 rpm. Samples were taken at different points of the growth curve. Cells were labelled with SNAP-surface 488 substrate and Hoechst. The fluorescence of SNAP-surface 488 and Hoechst, the combination of both signals (merge panels) and the differential interference contrast (DIC) images are shown. Scale bar of panels represents 5 μm. d Schematic representation of the fluorescence intensity profile of cross-section of individual cells. The fluorescence intensity was determined using the Intensity profile plugin of Icy-software. This plugin calculates the intensity value of each pixel along a cross-section line of 3 μm that was drawn on individual cells. S. aureus Bap-SNAP individual cell grown in LB (upper right panel) and in LB-glu (lower right panel) with cross-section draw was shown. Scale bar of panels represents 0.5 μm. e Graphs correspond to the mean of the intensity profiles of cross-sections cells (n = 40). Gray shadow corresponds to standard deviation of the mean.
